# Feasibility of a jacket that generates heat

1. Mar 8, 2015

### Kidphysics

Don't think anything like this has been posted, and this isn't HW, just curiosity from someone in OR from FL.

I'd like someone to play along with me here either help me out or rip me to pierces.

A few simple things: how would I calculate heat generation needed to make a person comfortable in very cold weather? Estimate a heat capacity, find the energy needed ..

Then I was thinking of power (P=IV). After I find the energy, I could try different times for the jacket to heat up in (lower power, less health risk). I can do these calculations but it would be fun to see what power would be needed to heat up in 2 mins, 3 mins, 15 mins/

How much current do you think I could get away with? Assuming insulating wires.. How much voltage?
V=IR. This might be a legal question. The human body is pretty weak as far as current tolerance.

Is a system of resistive wires (I assume my toaster has these wires) throughout the jacket the best way to do this or is there a sexier technique?

What type of material should the jacket be made from? I assume something with a high thermal conductance. Any ideas?

Any contribution helps and again, thanks for spit balling with me

2. Mar 8, 2015

### Staff: Mentor

Last edited by a moderator: May 7, 2017
3. Mar 8, 2015

### Kidphysics

Darn, guess it was feasible lol!

4. Mar 8, 2015

### SteamKing

Staff Emeritus
And it's been around for a while now.

Aircrews flying in B-17s over Europe wore flight jackets which were electrically heated. The jackets were plugged into and drew current from the plane's electrical system. The planes were not pressurized, and flying at altitude on bombing missions meant that temperatures could easily drop below zero Fahrenheit for several hours.

http://en.wikipedia.org/wiki/Flight_suit

Not all aircrew had the luxury of wearing heated suits. Many had to make due with unheated heavy clothing (and several layers of it), and frostbite due to exposure to the cold was a real hazard.

5. Mar 16, 2015

### diogenesNY

'Electric Socks' powered by small dry cell batteries are commonly available at any sporting goods store that caters to hunters. They are fairly inexpensive and if you spend a lot of time out of doors in frigid weather they can make you a LOT more comfortable. Try 'em!

diogenesNY